"impossible to prevent his praying"

Christians are called to devote themselves to prayer (Colossians 4:2). They are instructed to 'pray in the Spirit on all occasions with all kinds of prayers and requests' (Ephesians 6:8) and to 'not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, present your requests to God' (Philippians 4:6).

They are also called to pray, among other things, for God's will in their lives (Romans 1:10), for the peace of Jerusalem (Psalm 122:6) and salvation of the Israelites (Romans 10:1), for the love and knowledge of God (Philippians 1:9), and for the sick (James 5:14). 

Jesus in Prayer
Public DomainJesus in Prayer